Hi. Your clown loaches will get too big for that aquarium. I would find them a new home. The tetras are fine.
Cabomba sheds when it doesn't have enough light. This is probably your issue.
As you get more involved you will wish you had changed that rainbow gravel sooner. I would do it now before your plants grow in. Search on how to do it...it is quite simple. I would replace it with a single colour substrate of your choice.
Search for low-light plants like cryptocoryne, Anubias, java fern, mosses, etc and use your current light.